Household sponge



FIG. 1 is a top perspective view of the household sponge showing my new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof; and

FIG. 5 is a side elevational view thereof. 

The ornamental design for a household sponge, substantially as shown. 